Further characterization of the chick oviduct phosphoprotein phosphatase and improved procedures for purification of this enzyme are proposed. The effect of this phosphoprotein phosphatase on the structure and function of the chick oviduct chromatin will be examined. In addition, as a preliminary step towards the identification of the nuclear estrogen acceptor, we are examining the nature of estrogen binding in the high molecular weight chromatin which binds estrogen exclusively. An affinity chromatography column which is suitable for isolating the chromatin fraction with the nuclear acceptor site is being prepared. BIBLIOGRAPHIC REFERENCE: Studies on the Stability of Chromatin from Hen Oviduct. R. T. Franceschi and K. H. Kim, Arch. Biochem. Biophys. 176, 489, 1976.